A multipoint fuel injection device is known as a fuel injection control unit for an internal combustion engine installed in a vehicle. The multipoint fuel injection device includes: an in-cylinder injector that injects fuel into cylinders; and an intake path injector that injects fuel into an intake port, and controls the fuel injection through the in-cylinder injector and the fuel injection through the intake path injector in accordance with a driving state.
When the multipoint fuel injection device is used, exhaust gas can be purified with improved acceleration response and fuel efficiency. The fuel injection device injects fuel into the intake path when the engine is in a low load-low speed region to achieve a high intake air-fuel mixing performance for better ignition performance, and uses the fuel injection from both the intake path injector and the in-cylinder injector when the engine is in a high load-high speed region.
What is known as an idling stop function of forcibly stopping idling of the engine when the vehicle is at a halt has been featured in attempts to improve fuel efficiency.
The engine of a vehicle stops in two situations: a situation where the driving is ended; and a situation where the vehicle is brought to a halt but is intended to be restarted. In the former situation, an ignition key is turned OFF. The latter situation is achieved when any of the following conditions is satisfied: the vehicle speed is zero, the braking pedal has been stepped on, the accelerator operation amount is zero, the lever is set to be in a driving range, and the like. The engine in a vehicle having the idling stop function is stopped by an operation of an idling stop unit, in an ECU and the like, performed when a condition in question is satisfied.
A hybrid vehicle disclosed in Patent Document 1 is equipped with an internal combustion engine including: an in-cylinder fuel supply path including an in-cylinder injector; an intake path fuel supply path including an intake path injector; and an idling stop unit. This disclosed hybrid vehicle includes a unit that closes a relief valve of the in-cylinder fuel supply path at the time of idling stop, so that fuel pressure can be maintained at a high level. In this condition, fuel is injected into a cylinder from the in-cylinder fuel supply path when the engine is restarted after the idling stop condition is no longer satisfied, in an aim to ensure smooth start performance and prevent exhaust air purification function from deteriorating.
Patent Documents 2 and 3 each disclose an internal combustion engine that is installed in a vehicle and includes a control unit that drives a fuel pump before the engine is restarted so that fuel pressure in a fuel supply path rises to a level required for the starting by the time of the restarting of the engine, after the idling stop has been terminated with the idling stop condition no longer satisfied.